1. Field of the Invention
The present invention relates to a storage control apparatus and a method for controlling a storage control apparatus.
2. Description of the Related Art
Recent computer systems, such as those used in corporations, are configured using so-called open system computers (hereinafter referred to simply as “open computers”) such as personal computers and workstations.
However, in order to effectively use resources that have been accumulated throughout the years and to comply with demands such as high stability and high reliability, mainframe computers (or general-purpose computers; hereinafter referred to as “mainframes”) still remain in high demand, for example, in areas of online and backbone business. In recent years, for example, there are systems configured as “mixed systems” in which a mainframe is used where needed while open computers are employed for information-related jobs such as jobs involving decision-making and analysis.
Note that such a system is disclosed, for example, in U.S. Pat. No. 5,530,845. In this system, a mainframe and a plurality of open computers of different types are connected to a single storage control apparatus, and the storage control apparatus is emulated by a controller (Programmable Storage Controller).
For open computers, the FBA (Fixed Block Architecture) format, in which designation is made in terms of logical block address, is generally used as a recording format for the disk drives; on the other hand, for mainframes, the CKD (Count Key Data) format, in which designation is made in terms of cylinder numbers, head numbers, and record numbers, is employed as a recording format for the disk drives. Open computers can only access data stored in FBA format, while mainframes can only access data stored in CKD format. Therefore, open computers cannot directly use mainframe's data, and conversely mainframe cannot directly use open computers' data.
To avoid such an inconvenience, a mechanism is known in which, as shown in FIG. 6, conversion software 70 for converting CKD format data of a mainframe 10 into FBA format data of open computers 20 is made to run on the open computers 20, and the open computers 20 convert the recording format of data stored in a storage control apparatus 30. (See, e.g., Japanese Patent Application Laid-open Publication No. 9-258908.)
However, such a mechanism has the following problems:    (1) The conversion software 70 must be provided for each of the open computers 20, thus resulting in much time and effort for installation, upgrade and other maintenance work. Moreover, the conversion software 70 will consume resources such as the open computers' storage areas and processors.    (2) The user of the open computer has to perform the conversion. Therefore, the users will have to be aware of jobs associated with conversion.    (3) Data transfer associated with conversion boosts traffic of the communication lines between the storage control apparatus 30 and the open computers 20, thus putting stress on other communications. Additionally, conversion efficiency varies depending on the performance of the communication lines.    (4) Conversion is performed on the open computers 20. This affects processing of other programs executed on the open computers 20. Moreover, high processing capability is required of the open computers 20, thus resulting in increased equipment costs.    (5) Exclusive control is fundamentally required to allow the mainframe 10 and the open computers 20 to access data in the storage control apparatus 30. However, there is no mechanism available at present that provides effective exclusive control in a mixed system comprised of the mainframe 10 and the open computers 20. Designing such a mechanism afresh requires a considerable amount of time, effort, and cost. Therefore, the mechanism for exclusive control has to be made up for through appropriate management operations.